287796 - style.clip animation uses entire CPU

Status: RESOLVED WORKSFORME

(Core :: Web Painting, defect)

Description

[mjpvirtual]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040803
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-US; rv:1.7.2) Gecko/20040803

I am animating the clip boundaries on a GIF which is mostly transparent using an
assignment like:
obj.style.clip = 'rect(' + top + ' auto ' + bottom + ' auto)'
As the script runs, the amount of CPU it uses increases gradually until 100% on
2.4G CPU. Produces the correct output, though. Same on Firefox, too. Works fine
on IE. URL points to test case culled from larger file. Works fine if I animate
only the top or bottom boundary, leaving the other constant.

Reproducible: Always

Steps to Reproduce:
1. Load the web page at given URL
2. Click on the link at upper right: "Click here ..."
3. Animation iteration shown in status bar. Things start happening at iteration 22.

Actual Results:  
The image is gradually exposed. The amount of CPU gradually increases until
machine is 100% busy until script completes (121 iterations at 200mS each).

Expected Results:  
This script should consume a trivial % of the CPU.

Comment 1

[Bob Clary [:bc] (inactive)]

performance issue exists on 1.7x but not the trunk.

Comment 2

[Mats Palmgren (inactive)]

WFM, trunk Linux (1.7.2 also works fine).

[e-mail], please reopen this bug if you see the problem in a recent
nightly build:
http://ftp.mozilla.org/pub/mozilla.org/mozilla/nightly/latest-trunk/
http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-trunk/

-> WORKSFORME